1. Field of Invention
The invention relates to a circuit board and, in particular, to a circuit board with an antenna layout.
2. Related Art
Due to the progress of the wireless communication techniques, wireless communication devices are widely spread and become the mainstream of modern products such as the wireless network cards, personal digital assistants, mobile phones, Bluetooth earphones, etc. In the wireless communication devices, the antenna is an important element used for receiving and emitting wireless signals. Generally speaking, the conventional wireless communication devices are usually equipped with a circuit board, which is installed with an antenna and a circuit layout for processing signals. The antenna is used to receive and emit wireless signals. The signal processing circuit processes (modulates or demodulates) the wireless signals.
Since the antenna and the signal processing circuit are both formed on the above-mentioned circuit board, they are likely to interfere with each other, resulting in antenna characteristic shifts or efficiency lowering. Therefore, the antenna has to be tested (e.g. its polarization properties) once the entire circuit board is finished. Then, the antenna has to be modified according to the test results. For example, the dimension of the antenna might be changed, which is very inconvenient.
Moreover, as the antenna is disposed on the circuit board, its characteristics are thus restricted by the material of the circuit board. In view of the requirement of more compact wireless communication products, the volume of the circuit board is also shrinking. The space allocated for the antenna and the signal processing circuit is also limited. Accordingly, elements in the signal processing circuit may have serious interference with the antenna, causing low transmission efficiency of the circuit board. For example, if the height of a capacitor is far taller than the antenna, the transmitted data may be distorted.
Therefore, it is an important subject of the invention to provide a better circuit board design to avoid the above-mentioned problems.